What is a Speaker?

In car audio, speakers are the components that actually produce sound. The speakers produce sound when they receive an electrical signal from another source. Speakers were originally made for communication purposes but eventually made their way into the music world.The speakers used in an audio system determine the way it will sound. Many combinations of different types of speakers can be used to ensure the system plays the way it is desired to.

All cars today have a set of speakers in them. When speakers were first used in cars, they were mounted in the centre of the dash, where head units are today. Now, speakers are mounted in various places including the doors, the rear deck, the top of the dash, the A-pillars (front pillars), and other panels in the car.

Below you can see a common stock speaker placement in a sedan.

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The Different Types of Speakers

Tweeters (Highs)


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Tweeters are small speakers that produce very high frequencies. They are not commonly used in stock car stereos because music can still be played without them; however tweeters drastically improve sound quality. This is why they are almost always used in aftermarket sound systems and sometimes high-end stock stereos. Tweeters produce clearer and crisper treble than regular mid-range speakers. They are often mounted in the A-pillars (front pillars) or sometimes on top of other speakers. This will be covered under coaxial speakers.

Pictured above, on the left, is a tweeter mounted inside of a grill that allows it to move and project sound in different directions. The photos in the middle and on the right are the back and front of a simple tweeter without a grill or fancy casing.


Mid-Ranges (Mids)
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Mid-range speakers produce the frequencies in their name, mid-range frequencies. These frequencies are in the middle in between bass and treble. This does notmean they cannot produce bass or treble though. They are however, incapable of producing these frequencies with significant sound pressure level (loudness) without damaging the speaker or losing sound quality. They are the most common speakers found in cars today because they are great for most typical car stereo applications. Mid-range speakers are often placed mounted in doors and the rear deck, behind the headrests in sedan.

Pictured above are two basic, common mid-range speakers.


Coaxials (Mids & Highs)
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Coaxial speakers have multiple different speakers on one frame. In most cases, they consist of a tweeter paired up with a mid-range speaker. Usually, the tweeter is mounted above and in the centre of the mid-range speaker, as seen in the photos above. These speakers are space conserving because only a single mounting location is needed, as opposed to two if the tweeter and mid-range speakers were separate. Also, better sound quality can be produced in certain situations because the sound is being projected from one location. In some audio systems, it is possible to identify the direction in which certain frequencies are coming and this usually decreases sound quality in the system. Coaxial speakers are very common in aftermarket audio systems because of their benefits.

Pictured above are different coaxial speakers made by MTX and Rockford Fosgate.

Subwoofers (Lows)

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Subwoofers are speakers that are used to produce low frequencies. These speakers produce what is commonly called bass. The low, deep notes in music. In car audio, subwoofers are extremely common and are often the main feature of car sound systems. Subwoofers differ from other speakers because they require their own enclosure. Their enclosure is usually a box, made of different types of natural, or engineered woods like medium-density fibreboard (MDF). These enclosures are extremely important and are directly related to subwoofer performance. Subwoofers can range from sound quality speakers designed for clear bass, and others can be made maximum sound pressure level (loudness). Subwoofers come in many sizes usually including 8", 10", 12", 15" and sometimes 18" and 21". They are usually circular but some brands manufacture square shaped subwoofers. These speakers are usually placed in the trunk because their enclosures often require more room than is available inside the cabin of a car; however they can be placed under seats if they are small enough.

Pictured above, on the left, there is a Pioneer subwoofer used in many entry level systems. In the middle there is a square Kicker subwoofer that is considered a very controversial speaker. Many enthusiasts are on the fence about the abilities of this speaker. On the right, there is a very powerful 18" subwoofer. It is an Ascendant Audio SMD subwoofer capable of handling over 2500 watts of continuous power (RMS).



Below is a fully installed sound system using Alpine speakers. There are four 12" Alpine Type-R subwoofers and amplifiers and a capacitor (power storage device) being displayed. The system is enclosed in a painted fibre-glass housing. These types of sound systems are often used for car shows rather than competition because they sacrifice loudness for the clean, sleek appearance.
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Sources:
http://en.wikipedia.org/wiki/Car_audio
http://hometheater.about.com/cs/loudspeakers/a/aasubwoofera.htm
http://www.crutchfield.com/S-eorSPKrXefW/learn/learningcenter/car/speakers.html

Image Sources:
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http://www.drdetailshop.com/CO652andCO552Tweeter7lg.gif
http://withfriendship.com/images/i/40894/Tweeter-wallpaper.jpg
http://www.europe-audio.com/img/Data/HQ/sph-130al.gif
http://www.allinaudio.com/el/LM57.jpg
http://www.imshopping.com/showImageByKey.action?type=tnail&key=15wG0Ldq
http://icedotcomexpress.com/images/T1693_1_l.jpg
http://www.soarerworld.com/forum/attachment.php?attachmentid=10188&stc=1&d=1140710244
http://www.productwiki.com/upload/images/icker_solo_baric_s10l5.jpg
http://www.ascendantaudio.com/products/Ascendant/SMD/15/smd18inchlargeside.jpg
http://4.bp.blogspot.com/_bEL7GWGyzjM/TT1d4Vx0_vI/AAAAAAAAAeE/ab5HFFXT8A0/s1600/Car-Audio-Custom.jpg
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